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What the Information Tells Us About Bennett Lake <br />The most significant findings regarding Bennett Lake and its watershcd are as foliows: <br />■ Bennett Lake has poor water quality, characteristic of many urban lakes. <br />• An important contributing factor influencing the nutrient -enriched condition of the <br />lakc is the high nutrient loads from its large, mostly �rbanized watershed. Another <br />likely factor is the prevalence of the exotic aquatic weed curly-leaf pondweed, which <br />effectively "pumps" phosphorus out of the sediments ands releases it into the water <br />column during its annual die-off in the middle of the summer growing season. <br />• Based on modeling and other observations, a 40% reduction in phosphorus loads to <br />Bennett Lake would be needed in order Eo bring in-lake water quality up to the Grade <br />C range (average water quality for this region) on the Mct Council's scale. This is a <br />very large reduction and is likely to be achieved only with significant and expensive <br />infrastructure changes and i�tensive management activities in the lake itself. <br />■ The aquatic plant community is dominated by a few aggressive natives as vcrell as <br />exotics. This is likeiy due to both histaric water level fluctuations in the pond and <br />nutrient enriched conditions. <br />MANAGEibiE��' OPTIQNS <br />General Comments <br />Set�ina Expectations for Shallow Lakes <br />The pristine state of most shallow lakes is one of relatively clear r,vater and a diverse, t•ooted <br />aquatic plant community usually dominated by relatively small-sized plants. While algae are <br />presenl, they are not sufficiently abundant to create the turbid water conditions sufficient to <br />shade out Che rooted submerged plants. The increase in nutrient loading that often occurs with <br />the development of the lake's watershed changes this situation. The lake shifts from clear to <br />turbid �vater, and with this decrease in water clarity, submerged aquatic plants disappear. <br />Restoratic�n of turbid shallow lakes to the clear vejetated state is difficult. Recluction of nutrient <br />loadin�s from the watershed rnay have little aFfect, stnce durin� tl�e period of hi�h incoming <br />Ciri% of Roseville 52 <br />Parks Natr�ral Resorarce hlcrTragenaent <br />